Detection of boson peak and fractal dynamics of disordered system using terahertz spectroscopy

Abstract

Disordered systems exhibit universal excitation, referred to as the boson peak, in the terahertz region. Meanwhile, the so-called fracton is expected to appear in the nanoscale region owing to the self-similar structure of monomers in polymeric glasses. We demonstrate that such excitations can be detected using terahertz spectroscopy. For the interaction between terahertz light and the vibrational density of states of the fractal structure, we formulate an infrared light-vibration coupling coefficient for the fracton region. Accordingly, we show that information concerning fractal and fracton dimensions appears in the exponent of the absorption coefficient. Finally, using terahertz time-domain spectroscopy and low-frequency Raman scattering, we experimentally observe these universal excitations in a protein lysozyme system that has an intrinsically disordered and self-similar nature in a single supramolecule. These findings are applicable to disordered and polymeric glasses in general and will be key to understanding universal dynamics of disordered systems by terahertz light.

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Cited by in corpus (11)

• Near-field localization of the boson peak on tantalum films for superconducting quantum devices
• Low-Frequency Vibrational States in Ideal Glasses with Random Pinning
• Physics of Phonon-Polaritons in Amorphous Materials
• Understanding the scaling of boson peak through insensitivity of elastic heterogeneity to bending rigidity in polymer glasses
• Structural and mechanical characteristics of sphere packings near the jamming transition: From fully amorphous to quasi-ordered structures
• Phonon transport properties of particulate physical gels
• The connection between polymer collapse and the onset of jamming
• Protein folding as a jamming transition
• Unified study of viscoelasticity and sound damping in hard and soft amorphous solids
• Structural fluctuations in active glasses
• Structural, mechanical, and vibrational properties of particulate physical gels